The present invention relates to a safety spray head, particularly for high-pressure spray guns comprising a rotary part positioned in a central body and containing a through channel that has a spray orifice and a seal to prevent leaks between the rotary part and the gun.
American patent U.S. Pat. No. 3,952,955 shows a spray head with a protective nozzle comprising a mechanism for alignment with the said head.
U.S. Pat. No. 3,955,763 describes a spray head for attachment to the diffuser of a spray gun, the nozzle comprising a rotary part in the form of a ball containing a spray orifice formed in a circular channel. This nozzle comprises a casing surrounding the rotary part and a sealing member positioned in the casing and applied leaktightly against the rotary part. The casing, the rotary part and the sealing member are assembled in a single operation by screwing them onto the diffuser of the spray gun. When the user wishes to change the nozzle he has to separate the nozzle from the diffuser of the gun and then assemble its various components before proceeding, in a single operation, to reassemble the nozzle on the gun diffuser. The user may experience difficulties during this operation because the nozzle components must be in the ideal position
This nozzle is therefore intended to be mounted on a single type of gun and so cannot be adapted to all existing guns.
U.S. Pat. No. 4,629,121 presents a nozzle with a flow-controlling shut-off valve that comprises a frame with an inlet and an outlet on opposite sides. The controlling p art situated inside the frame can rotate on an axis perpendicular to the flow, which it intercepts.
U.S. Pat. No. 4,508,268 presents a reversible spray head for use with spray guns and devices for spraying liquids such as paints, comprising a frame, an interchangeable rotary part mounted transversely to the frame, having a bore ending in a spray opening through which the liquid passes with a shut-off part sliding in the frame that engages the rotary part and that has a passage for communication between the bore of the rotary part and the high-pressure liquid source.
Swiss patent CH 655, 867 shows us a head that already has a rotary part, this part comprising a circular groove. The central body comprises a bore and between the two it is possible to insert a seal that exhibits a cross section that adapts to this geometrical form and that allows a rotary part to be guided, positioned and maintained in its cavity inside the central body.
If the heads are not reversible it is necessary to remove their nozzles in order to clean them, whereas if they are reversible this operation is very simple and is usually done by turning a rotary part which contains it [sic]. Nonetheless, it must be remembered that nozzles have a limited life because they are used with high-pressure fluids, many of which are erosive and produce wear which modifies the geometry of the nozzle.
The life of a nozzle can be extended if manufactured from more wear resistant materials such as tungsten carbide, but even so at some stage it will still have to be replaced. As a consequence it is clear that a simple operation for dismantling this rotary part containing the nozzle in order to replace it is still desirable.
The present invention seeks to mitigate these problems and to propose a head with a rotary part of extremely simple design that makes it possible to open the passage for the fluid under pressure and to stop it. It is self-cleaning and easily detachable for changing the rotary part containing the spray nozzle. separated from the gun so that the rotary part can be extracted from the central body.
The top of the supporting seat advantageously has a concave shape so that the contact with the spherical portion of the rotary part facilitates the relative movement of one component against the other.
In a preferred embodiment, the rotary part is connected to a handle that enables it to be turned by as much as a semicircle between two extreme positions, and a lip provided on the handle and having two flat opposite surfaces abuts against the top surface of the gripping adaptor upon rotation in such a way [lacuna] the two positions are fixed.
The spray head may advantageously posses a guard around the nozzle for the protection of the user.
This configuration has the advantage that the handle can be reversed by 180xc2x0. This allows cleaning by reversing the position of the handle. Again the construction permits extremely easy dismantling of the components owing to the fact that the nut connecting the gun to the head has simply to be unscrewed in order to release the seal which is pushed via the base by the action of the spring. The rotary part can thus be withdrawn.